Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents
  • D21C9/06—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents in filters ; Washing of concentrated pulp, e.g. pulp mats, on filtering surfaces
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D33/00—Filters with filtering elements which move during the filtering operation
  • B01D33/06—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums
  • B01D33/073—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums arranged for inward flow filtration
  • B01D33/09—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums arranged for inward flow filtration with surface cells independently connected to pressure distributors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D33/00—Filters with filtering elements which move during the filtering operation
  • B01D33/44—Regenerating the filter material in the filter
  • B01D33/46—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element
  • B01D33/463—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element nozzles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D33/00—Filters with filtering elements which move during the filtering operation
  • B01D33/44—Regenerating the filter material in the filter
  • B01D33/46—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element
  • B01D33/466—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element scrapers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D33/00—Filters with filtering elements which move during the filtering operation
  • B01D33/58—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element
  • B01D33/60—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for washing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D33/00—Filters with filtering elements which move during the filtering operation
  • B01D33/58—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element
  • B01D33/62—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying
  • B01D33/64—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying by compression
  • B01D33/644—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying by compression by pressure plates, membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D33/00—Filters with filtering elements which move during the filtering operation
  • B01D33/58—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element
  • B01D33/62—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying
  • B01D33/64—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying by compression
  • B01D33/646—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying by compression by pressure rollers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D33/00—Filters with filtering elements which move during the filtering operation
  • B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
  • B01D33/72—Filters with filtering elements which move during the filtering operation having feed or discharge devices for feeding
  • B01D33/722—Filters with filtering elements which move during the filtering operation having feed or discharge devices for feeding containing fixed liquid displacement elements or cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D33/00—Filters with filtering elements which move during the filtering operation
  • B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
  • B01D33/76—Filters with filtering elements which move during the filtering operation having feed or discharge devices for discharging the filter cake, e.g. chutes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2201/00—Details relating to filtering apparatus
  • B01D2201/28—Position of the filtering element
  • B01D2201/282—Filtering elements with a horizontal rotation or symmetry axis

Definitions

• the invention concerns so-called drum washers, which are used especially for washing pulp suspensions in the cellulose industry.
• Drum washers have a rotatable cylindrical drum, which is permeable to washing liquid and onto the case of which the pulp to be washed is fed constantly to form a mat. Washing liquid is conducted onto the top of the mat and it then passes through the mat and the case and enters the drum, from which it is removed through the drum end. The washed pulp is worked loose and removed from the periphery.
• Drum washers are known wherein a mat is formed on the case and in the lower drum part with the aid of a special compression plate assembly. In this way the washing zone in the drum is lengthened.
• a washer is described e.g. in patent specifica ⁇ tion FI-C-55370. GENERAL DESCRIPTION OF THE INVENTION
• the purpose of this invention is above all to bring about a drum washer with as long a washing step as possible which works without disturbances.
• FIG. 1 shows an end view of the washer and of the washing process as seen from one end of the washing drum
• FIG. 3a and 3b show an enlarged view of a detail of the washer's compression plate assembly as seen from one end of the drum.
• the main components of the washer are a basin 1 attached to the body which has a rotatable filtering drum 2, a feeding assembly 3 for the pulp to be washed, a washing water feeding assembly 4, a washing water circulation piping 5, an assembly 6 for removing washing water and an assembly 7 for removing washed pulp.
• the filtering drum has a cylindrical case 9 permeable to washing water and mounted on the shaft 8.
• the shaft ends protrude from the open ends of the drum into bearings attached to the body.
• the drum rotates clockwise as seen in Figure 1.
• the case 9 ends are provided with flanges 10. Their exterior side carries sealing means 11 matching with the basin ends ( Figure 2) .
• Pulp to be washed is supplied into the basin and by way of an assembly 13 to an approximate four - five o'clock position in relation to the axis of rotation.
• the pulp flow 12 fed into the basin is guided to form a mat against the drum case 9 by a guiding plate 14 which is parallel with the case.
• the front end of the guiding plate is journalled tightly in the bottom wall 15 of the basin on a shaft 16 which is coaxial with the drum shaft.
• the distance between guiding plate and drum periphery is adjustable by using bars 17.
• a follower plate 18 is located after the guiding plate. Its back end is journalled tightly in a partition wall 19 on a shaft 20.
• the partition is located in an approximate eight - nine o'clock position in the drum's direction of rotation.
• the distance between follower plate and drum periphery is adjustable by using bars 21.
• a gap 22 is left between the plates.
• washing water feeding space 23 The bottom wall 15 of the basin, the guiding plate 14, the follower plate 18 and the partition 19 form a washing water feeding space 23. Washing water is supplied to this space by way of an assembly 24. The washing water flows through gap 22 onto the pulp mat and further through this and through the drum periphery and enters the drum.
• the back edge of guiding plate 14 is extended by a flexible lip 25 which presses on the follower plate 18 from the drum side.
• the lip functions in gap 22 as a flap valve which prevents pulp from entering the washing water feeding space 23.
• Below the lip there are lip supporting forks 26, which are articulated to the follower plate. Their free ends are located on top of the guiding plate extension.
• a pulp mat compression plate 28 forms an extension to the follower plate 18.
• the upper part of the basin is closed tightly by a hood 27.
• the bottom wall 15 of the basin, its partition 19 and the hood 27 mark the limits of a second-step washing water feeding box 29. Washing water can be fed into the box through an assembly 30.
• a positive pressure e.g. 0.3 bar
• the positive pressure furthers the transfer of washing water through the mat.
• a mat removal device for working loose the mat from the drum and moving it into a chute 35.
• the pulp is removed from the chute into line 36 by a screw conveyor.
• the chute may also have pulp mat comminutor means 37, for example, suitable obstacles. Diluting water is also fed into the chute by way of assembly 38.
• the filtrate collecting on the drum bottom leaves through an aperture 39 in the basin end.
• the top edge of the pulp feeding assembly 13 is sealed against the drum periphery. In this way an overflow area 40 is formed which assists in keeping the filtrate level in the drum at a constant level.
• the water passing through the drum also cleans the case 9 holes removing any attached fibres. From area 41 above the overflow area air flows through the holes due to the positive pressure in the chamber and this air also cleans out the holes.
• a cleaning scraper 42 is also provided in front of the overflow area. Any overflow and the fibres ending up in it are removed by way of line 43.
• the filtrate obtained from the upper part of the drum in the final washing step is of course cleaner than the filtrate of the early step.
• This cleaner filtrate is recovered separately into collecting troughs 44 which are located below the drum shaft ends and from which the filtrate is removed along lines 45.
• the drum shaft 8 has two fixed.similar circular-based cones 46 which are placed with their bases against one another.
• a flange 47 extends along their bottom seam and this flange is attached to the drum case 9 by radial support bars so that air is allowed to pass between the case and the flange.
• Vanes 48 are attached to the surface of each cone 46.
• the vanes are essentially triangular. A straight gap is left between the vane and the drum case 9.
• the filtrate arriving in the upper part of the drum through the drum case 9 falls onto the vanes 48, along which it runs onto the cone 46 surface and further into a collecting trough 44 located below the shaft 8 end.
• the vanes 48 are not located radially, but they are turned slightly backwards in the direction of rotation. In this way that sector is reduced from which filtrate is collected. In the embodiment shown by the figures the collection of filtrate starts approximately 45° before the top vane position.
• the vanes 48 may be provided with grooves or corrugations 49, which guide the flow toward the cone 46 surface (figure 2).
• the rigidity of the vanes is increased at the same time.
• the speed of rotation of the drum must not be allowed to become so high that the centrifugal force would begin making the filtrate run with greater difficulty on the vanes 48.
• a suitable speed of rotation is e.g. 0.5 - 6 revolutions per minute.
• the cleaner filtrate collected into troughs 44 may be used, for example, in the same washer as washing water supplied to the first step.
• the pressurized air conducted into the hood 27 is taken from the pulp exit side from the pulp screw space limited by partition 31 with the aid of a pump 50 and by way of line 51. In this way a low pressure is created on the exit side to assist in moving the washing water and in working loose the pulp from the case 9.
• a cleaning scraper 52 may also be connected with the sealing roller 32.
• the washing water feeding space 23 and the air space in hood 27 are interconnected by a pressure pipe 53.
• the positive pressure in the hood is made to affect the feeding space 23 as well.
• the pipe functions as a safety device which balances the water pressure in the feeding space 23.
• Pressure indicators are connected to the equipment at various points to make possible adjustments of e.g. the pressure and speed of rotation according to their indications.
• An advantage of the compression plate arrangement of the invention is that even if the pulp feeding pressure should exceed the washing water feeding pressure (e.g. when starting up), the water will be filtrated from the pulp mat into the drum. Thus, the device can be used even if no washing water is fed to the first step.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Paper (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8532723

Family Applications (1)

Country Status (6)

Cited By (6)

Families Citing this family (6)

Citations (4)

Family Cites Families (8)

• 1991
  • 1991-06-17 FI FI912920A patent/FI88940C/fi active IP Right Grant
• 1992
  • 1992-06-17 AU AU18979/92A patent/AU1897992A/en not_active Abandoned
  • 1992-06-17 JP JP51075592A patent/JP3232332B2/ja not_active Expired - Fee Related
  • 1992-06-17 WO PCT/FI1992/000187 patent/WO1992022702A1/en active Application Filing
  • 1992-06-17 CA CA002109573A patent/CA2109573A1/en not_active Abandoned
  • 1992-06-17 US US08/142,336 patent/US5421176A/en not_active Expired - Fee Related

Patent Citations (4)

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